Advanced radar absorbing ceramic-based materials for multifunctional applications in space environment

In this review, some results of the experimental activity carried out by the authors on advanced composite materials for space applications are reported. Composites are widely employed in the aerospace industry thanks to their lightweight and advanced thermo-mechanical and electrical properties. A critical issue to tackle using engineered materials for space activities is providing two or more specific functionalities by means of single items/components. In this scenario, carbon-based composites are believed to be ideal candidates for the forthcoming development of aerospace research and space missions, since a widespread variety of multi-functional structures are allowed by employing these materials. The research results described here suggest that hybrid ceramic/polymeric structures could be employed as spacecraft-specific subsystems in order to ensure extreme temperature withstanding and electromagnetic shielding behavior simultaneously. The morphological and thermo-mechanical analysis of carbon/carbon (C/C) three-dimensional (3D) shell prototypes is reported; then, the microwave characterization of multilayered carbon-filled micro-/nano-composite panels is described. Finally, the possibility of combining the C/C bulk with a carbon-reinforced skin in a synergic arrangement is discussed, with the aid of numerical and experimental analyses

Technology challenges of stealth unmanned combat aerial vehicles

The ever-changing battlefield environment, as well as the emergence of global command and control architectures currently used by armed forces around the globe, requires the use of robust and adaptive technologies integrated into a reliable platform. Unmanned Combat Aerial Vehicles (UCAVs) aim to integrate such advanced technologies while also increasing the tactical capabilities of combat aircraft. This paper provides a summary of the technical and operational design challenges specific to UCAVs, focusing on high-performance, and stealth designs. After a brief historical overview, the main technology demonstrator programmes currently under development are presented. The key technologies affecting UCAV design are identified and discussed. Finally, this paper briefly presents the main issues related to airworthiness, navigation, and ethical concerns behind UAV/UCAV operations

Polymer Composites for Electrical and Electronic Engineering Application

Polymer composite materials have attracted great interest for the development of electrical and electronic engineering and technology, and have been widely applied in electrical power systems, electrical insulation equipment, electrical and electronic devices, etc. Due to the significant expansion in the use of newly developed polymer composite materials, it is necessary to understand and accurately describe the relationship between composite structure and material properties, as only based on thorough laboratory characterization is it possible to estimate the properties for their future commercial applications. This book focuses on polymer composites applied in the field of electrical and electronic equipment, including but not limited to synthesis and preparation of new polymeric materials, structure–properties relationship of polymer composites, evaluation of materials application, simulation and modelling of material performance

A Future-Based Risk Assessment for the Survivability of Long Range Strike Systems

The United States Air Force today faces the challenge of allocating development resources to prepare for future force projection requirements. In particular, the Air Force\u27s core competency of Global Attack implies a future capability that can quickly and successfully deliver combat effects anywhere in the world with impunity. Understanding that the future threat environment is dynamic and that continued advancements by adversaries will likely degrade the technical superiority of today\u27s weapon systems, the need arises for a planning model to direct development funding to areas with the greatest probability of successfully defending the strike vehicle of 2035. Examining this problem posed two distinct challenges. The first was to determine the most likely course of Integrated Air Defense System technology through the time period of interest--allowing for plausible disruptive technologies that generate orders-of-magnitude improvement in capability or even change the nature of air defense systems. The second challenge was to characterize future adversaries--requiring a broad look at political and economic trends as presented in AF 2025, SPACECAST 2020 and other relevant future studies. Based on these studies, threat scenarios were generated from technical assessments of emerging technologies and evaluated using the Risk Filtering, Ranking and Management (RFRM) technique (Haimes, 2004) to explore the most severe threats to a future global strike air vehicle. The application of RFRM to the problem created a coherent threat hierarchy that enables the decision maker to examine anticipated hostile systems that may counter key U.S. strengths of stealth, speed, and high altitude operations. Those threat scenarios were then evaluated using decision trees and sensitivity analysis to demonstrate how quantitative tools can be applied to a largely qualitative problem

Performance and Wearability of Electronic and Infrared Stealth Textiles

The functionality of smart textiles continues to make progress, but its wearability is often not guaranteed at the same time. The rough and porous fabric surface, the added materials (eg. electronic materials) not possessing characteristics like breathability and drape, and inadequate research are the main reasons leading to this problem. In this work, two kinds of smart textiles, electronic textiles (e-textiles) and infrared stealth fabrics, are studied to improve their performance and ensure their wearability meanwhile. This work provides ideas and theoretical guidance for the development of these and similar smart textiles in the future. Using thermoplastic polyurethane (TPU) film as an intermediate layer for printing e-textiles is very common as it provides a smooth surface for device deposition, leading to improved device performance. However, at the same time, the TPU interferes with many desirable properties of the fabric, which makes textiles less comfortable to wear. In order to reduce the impact of TPU film on the wearability of e-textiles, the effects of different TPU types and processing conditions on electronic textile properties are investigated for the first time. It is found that the increase of TPU film thickness can improve the electrical conductivity and stretchability of e-textiles. On the other hand, the drape, water vapor permeability (WVP) and thermal conductivity of textiles decreases. Lower density TPU types are better because they have improved WVP and heat transfer, while electrical conductivity and stretchability are unaffected. Compared to single-layered TPU films, double-layered TPU can greatly improve the electrical conductivity and stretchability of e-textiles because they have better deformation resistance and can isolate the conductive layer and the fabric, reducing the impact of the fabric on the conductive layer. Increasing the curing temperature can improve the electronic performance of the e-textiles, but higher temperatures cause the TPU films to melt and curl. Finally, increasing the laminating temperature and laminating time can effectively improve the electrical properties of e-textiles, but the rigidity of e-textiles becomes larger. These results provide guidance to achieve a more seamless integration of electronics into textiles. Due to the high surface roughness of fabric, most of the coatings that exert good infrared stealth performance on a flat substrate have greatly weakened performance on fabric. Worse still, these materials severely interfere with the original properties of fabrics after coating. To solve this problem, silver nanowires (AgNWs) are considered for the first time in the preparation of infrared stealth fabrics and found to be very suitable. First of all, due to its metallic characteristics, it can provide a low infrared emissivity for the coating. And compared with other forms of silver structures, it has the advantages of low gloss, fitting degree with fabric, and high transparency in the visible light region. In the optimization of AgNW parameters, it is found that AgNWs with smaller diameters have better infrared stealth effect. AgNW array agglomeration and arrangement phenomenon reduce the infrared stealthing performance of the coating. Adding resin to AgNW solution may better disperse AgNWs and reduce agglomeration and arrangement phenomenon. But the resin's absorption of infrared rays is also noteworthy. It is found that increasing curing time has no significant effect on the infrared reflectance of AgNW array but can improve the electrical conductivity of AgNW array. This shows that instead of electron movement between nanowires, the vibration of electrons in single nanowires determines their stealth properties

Unmanned Aircraft Systems in the Cyber Domain

Unmanned Aircraft Systems are an integral part of the US national critical infrastructure. The authors have endeavored to bring a breadth and quality of information to the reader that is unparalleled in the unclassified sphere. This textbook will fully immerse and engage the reader / student in the cyber-security considerations of this rapidly emerging technology that we know as unmanned aircraft systems (UAS). The first edition topics covered National Airspace (NAS) policy issues, information security (INFOSEC), UAS vulnerabilities in key systems (Sense and Avoid / SCADA), navigation and collision avoidance systems, stealth design, intelligence, surveillance and reconnaissance (ISR) platforms; weapons systems security; electronic warfare considerations; data-links, jamming, operational vulnerabilities and still-emerging political scenarios that affect US military / commercial decisions. This second edition discusses state-of-the-art technology issues facing US UAS designers. It focuses on counter unmanned aircraft systems (C-UAS) – especially research designed to mitigate and terminate threats by SWARMS. Topics include high-altitude platforms (HAPS) for wireless communications; C-UAS and large scale threats; acoustic countermeasures against SWARMS and building an Identify Friend or Foe (IFF) acoustic library; updates to the legal / regulatory landscape; UAS proliferation along the Chinese New Silk Road Sea / Land routes; and ethics in this new age of autonomous systems and artificial intelligence (AI).https://newprairiepress.org/ebooks/1027/thumbnail.jp

DRONE DELIVERY OF CBNRECy – DEW WEAPONS Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD)

Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD) is our sixth textbook in a series covering the world of UASs and UUVs. Our textbook takes on a whole new purview for UAS / CUAS/ UUV (drones) – how they can be used to deploy Weapons of Mass Destruction and Deception against CBRNE and civilian targets of opportunity. We are concerned with the future use of these inexpensive devices and their availability to maleficent actors. Our work suggests that UASs in air and underwater UUVs will be the future of military and civilian terrorist operations. UAS / UUVs can deliver a huge punch for a low investment and minimize human casualties.https://newprairiepress.org/ebooks/1046/thumbnail.jp

Fast GO/PO RCS calculation: A GO/PO parallel algorithm implemented on GPU and accelerated using a BVH data structure and the Type 3 Non-Uniform FFT

The purpose of this PhD research was to develop and optimize a fast numeric algorithm able to compute monostatic and bistatic RCS predictions obtaining an accuracy comparable to what commercially available from well-known electromagnetic CADs, but requiring unprecedented computational times. This was realized employing asymptotic approximated methods to solve the scattering problem, namely the Geometrical Optics (GO) and the Physical Optics (PO) theories, and exploiting advanced algorithmical concepts and cutting-edge computing technology to drastically speed-up the computation. The First Chapter focuses on an historical and operational overview of the concept of Radar Cross Section (RCS), with specific reference to aeronautical and maritime platforms. How geometries and materials influence RCS is also described. The Second Chapter is dedicated to the first phase of the algorithm: the electromagnetic field transport phase, where the GO theory is applied to implement the “ray tracing”. In this Chapter the first advanced algorithmical concept which was adopted is described: the Bounding Volume Hierarchy (BVH) data structure. Two different BVH approaches and their combination are described and compared. The Third Chapter is dedicated to the second phase of the calculation: the radiation integral, based on the PO theory, and its numerical optimization. Firstly the Type-3 Non-Uniform Fast Fourier Transform (NUFFT) is presented as the second advanced algorithmical tool that was used and it was indeed the foundation of the calculation of the radiation integral. Then, to improve the performance but also to make the application of the approach feasible in case of electrically large objects, the NUFFT was further optimized using a “pruning” technique, which is a stratagem used to save memory and computational time by avoiding calculating points of the transformed domain that are not of interest. To validate the algorithm, a preliminary measurement campaign was held at the headquarter of the Ingegneria Dei Sistemi (IDS) Company, located in Pisa. The measurements, performed on canonical scatterers using a Synthetic Aperture Radar (SAR) imaging equipment set up on a planar scanner inside a semi-anechoic chamber, are discussed

Graphene-enabled adaptive infrared textiles

Interactive clothing requires sensing and display functionalities to be embedded on textiles. Despite the significant progress of electronic textiles, the integration of optoelectronic materials on fabrics remains as an outstanding challenge. In this Letter, using the electro-optical tunability of graphene, we report adaptive optical textiles with electrically controlled reflectivity and emissivity covering the infrared and near-infrared wavelengths. We achieve electro-optical modulation by reversible intercalation of ions into graphene layers laminated on fabrics. We demonstrate a new class of infrared textile devices including display, yarn, and stretchable devices using natural and synthetic textiles. To show the promise of our approach, we fabricated an active device directly onto a t-shirt, which enables long-wavelength infrared communication via modulation of the thermal radiation from the human body. The results presented here provide complementary technologies which could leverage the ubiquitous use of functional textiles

Optically transparent UWB antenna for wireless application & energy harvesting

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Transparent UWB antennas have been the focus of this PhD research. The use of transparent UWB antennas for stealth and energy harvesting has been the underlying applications that have given impetus to this research. Such transparent antennas being built on materials that are discreet, flexible, conformal, conductive and having the ability to provide good antenna performance on glass to serve as the ‘last mile’ link in subsequent generation communications after 4G have been the basis for this contention. UWB in this regard is able to provide the transmission and reception of high data rates and fast video transmission that is an elementary demand of even a 4G wireless communications system. The integration of UWB antennas with photovoltaic to provide integral energy harvesting solutions that will further enhance the value of the UWB system in terms of cost effectiveness and performance are thus the basis of this work. This work hence starts with the study of a transparent conductive oxide polymer, AgHT and its properties, and culminates in the development of a transparent UWB antenna, which can be integrated with photovoltaic for window glass applications on homes and buildings. Other applications such transparent antennas can find use for like on-body wireless communications in healthcare monitoring was also analysed and presented. The radar absorbing material (RAM) property of the AgHT was investigated and highlighted using CST simulation software, as no measurement facilities were available. The transparent UWB antenna in lieu of the inherent absorbent property of the AgHT material is thus able to exhibit stealth characteristics, a feature that would be much desired in military communications. Introduction of a novel method of connecting the co-axial connector to the feed of the antenna to improve gain and efficiency of transparent polymer based antennas and the development of a UWB antenna that maintains its Omni-directional characteristic instead of becoming directional on an amorphous silicon solar cell are presented as some of the contributions for this research work. Some preliminary analysis on the impact of glass on UWB antennas for video transmission and how to improve transmission is presented. The ability of the conductive part of the antenna radiator to be used as a RF and microwave harvester and how it can further add value to a transparent UWB antenna is presented by way of experimental data. Finally yet importantly, this thesis presents some insight into how transparent antennas may be used in Green Technology Buildings to provide an integrated solution for both wireless communications and energy harvesting as part of the future work. Improvement to the aesthetics of the external appearance of residential buildings through the integration of transparent satellite dish onto solar panels on rooftops is also discussed and illustrated as part of this future work